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Originally MS-DOS was designed to be an operating system that could run on any computer with a 8086-familymicroprocessor. It competed with other operating systems written for such computers, such as CP/M-86 and UCSD Pascal. Each computer would have its own distinct hardware and its own version of MS-DOS, a situation similar to the one that existed for CP/M, with MS-DOS emulating the same solution as CP/M to adapt for different hardware platforms. So there were many different original equipment manufacturer (OEM) versions of MS-DOS for different hardware. But the greater speed attainable by direct control of hardware was of particular importance, especially when running computer games. So very soon an IBM-compatible architecture became the goal, and before long all 8086-family computers closely emulated IBM hardware, and only a single version of MS-DOS for a fixed hardware platform was all that was needed for the market. This specific version of MS-DOS is the version that is discussed here, as all other versions of MS-DOS died out with their respective systems. One version of such a generic MS-DOS (Z-DOS) is mentioned here, but there were dozens more. All these were for personal computers that used an 8086-family microprocessor, but which were not fully IBM PC compatible.

^ abMS-DOS 8.0 has most of the functionality of prior versions, but with significant losses of usability, e.g., the loss of FORMAT /S command, that can be substituted by formatting HDD/FDD and then copying IO.SYS from CD-ROM boot A: image, as first ever file onto drive; loss of SYS A: (or SYS B:) command for floppies, that can be substituted too in the same way as FORMAT /S; inability to boot to a command prompt without substitution/modification of IO.SYS (other than CD-ROM boot version) and COMMAND.COM. For purpose of booting from C: drive, an unmodified IO.SYS from simulated A: boot diskette image, that is placed on Windows Me OEM CD-ROM, from which that CD boots, can be used, and English COMMAND.COM can be modified by replacing in this file at hex offset 00006510h byte 75h by byte EBh, or substituted by (now freeware) 4DOShttp://www.jpsoft.com/download.htm

^While Windows ME support ended, a version of its underlying DOS is included with Windows XP. When one formats a floppy in Windows XP and selects "Create an MS-DOS startup disk", the floppy is formatted with a DOS version that identifies itself as "Windows Millennium Version 4.90.3000".

^DR-DOS 8.1 was pulled from the market after it was discovered that 8.1 code had been copied from FreeDOS in violation of the GPL license.

^"Phystechsoft". Retrieved 2016-09-19. PTS-DOS 32 [..] Memory Manager himem.sys, included in PTS-DOS 32, supports up to 4 GB of RAM.PTS-DOS 2000 [..] PTS-DOS is a powerful and fast 16-bit disk operating system, fully compatible with MS-DOS and all its applications.

^ abScott Mueller (1995). Upgrading and Repairing PCs, 5th Edition. Que Corporation. ISBN0-7897-0321-1. p784: "The limit of 16MB did not come from the FAT, but from the high-level DOS FORMAT command... Most vendors supplied modified high-level format programs that permitted partitions of up to 32MB to be formatted properly."

^ abAs stated at http://support.microsoft.com/default.aspx?scid=KB;EN-US;Q184006& Microsoft's KB article 184006, the limit of 124.55 GB for FAT32 partition size is a mainly a limit of Windows 95/98's 16-bit SCANDISK utility. Other DOS versions supporting FAT32 may allow a larger partition size closer to the theoretical 2 TB/16 TB maximum suggested by FAT32's specifications. Windows 2000 and XP can mount and use a FAT32 partition larger than 32 GB, but they cannot natively create one, which according to Microsoft is by design.

^DOS Plus 2.1e/g versions for the Apricot ACT series and for the T.R.A.N. Yasmin Turbo support a non-standard single-sided 315 KB FAT12 format.

^DOS Plus DISK.CMD versions for the Amstrad PC1512 and T.R.A.N. Yasmin Turbo and the BBC Master 512 support variants of 720 KB FAT12 formats including the original MS-DOS, and PC DOS format, however known versions of DOS Plus itself don't make use of them.